switch surface to sk_sp

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1817383002
CQ_EXTRA_TRYBOTS=client.skia.compile:Build-Ubuntu-GCC-x86_64-Release-CMake-Trybot,Build-Mac-Clang-x86_64-Release-CMake-Trybot

Review URL: https://codereview.chromium.org/1817383002
diff --git a/gm/drawatlas.cpp b/gm/drawatlas.cpp
index 4d2f6d4..334aba7 100644
--- a/gm/drawatlas.cpp
+++ b/gm/drawatlas.cpp
@@ -13,9 +13,9 @@
 class DrawAtlasGM : public skiagm::GM {
     static sk_sp<SkImage> MakeAtlas(SkCanvas* caller, const SkRect& target) {
         SkImageInfo info = SkImageInfo::MakeN32Premul(100, 100);
-        SkAutoTUnref<SkSurface> surface(caller->newSurface(info));
+        auto surface(caller->makeSurface(info));
         if (nullptr == surface) {
-            surface.reset(SkSurface::NewRaster(info));
+            surface = SkSurface::MakeRaster(info);
         }
         SkCanvas* canvas = surface->getCanvas();
         // draw red everywhere, but we don't expect to see it in the draw, testing the notion